"""Hooks management

Hooks are called before / after any individual update of entities / relations

in the repository.

Here is the prototype of the different hooks:

* filtered on the entity's type:

  before_add_entity    (session, entity)

  after_add_entity     (session, entity)

  before_update_entity (session, entity)

  after_update_entity  (session, entity)

  before_delete_entity (session, eid)

  after_delete_entity  (session, eid)

* filtered on the relation's type:

  before_add_relation    (session, fromeid, rtype, toeid)

  after_add_relation     (session, fromeid, rtype, toeid)

  before_delete_relation (session, fromeid, rtype, toeid)

  after_delete_relation  (session, fromeid, rtype, toeid)

:organization: Logilab

:copyright: 2001-2009 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.

:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr

:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses

"""

__docformat__ = "restructuredtext en"

ENTITIES_HOOKS = ('before_add_entity',    'after_add_entity',

                  'before_update_entity', 'after_update_entity',

                  'before_delete_entity', 'after_delete_entity')

RELATIONS_HOOKS = ('before_add_relation',   'after_add_relation' ,

                   'before_delete_relation','after_delete_relation')

SYSTEM_HOOKS = ('server_backup', 'server_restore',

                'server_startup', 'server_shutdown',

                'session_open', 'session_close')

ALL_HOOKS = frozenset(ENTITIES_HOOKS + RELATIONS_HOOKS + SYSTEM_HOOKS)

class HooksManager(object):

    """handle hooks registration and calls

    """

    verification_hooks_activated = True

    def __init__(self, schema):

        self.set_schema(schema)

    def set_schema(self, schema):

        self._hooks = {}

        self.schema = schema

        self._init_hooks(schema)

    def register_hooks(self, hooks):

        """register a dictionary of hooks :

             {'event': {'entity or relation type': [callbacks list]}}

        """

        for event, subevents in hooks.items():

            for subevent, callbacks in subevents.items():

                for callback in callbacks:

                    self.register_hook(callback, event, subevent)

    def register_hook(self, function, event, etype=''):

        """register a function to call when <event> occurs

        <etype> is an entity/relation type or an empty string.

        If etype is the empty string, the function will be called at each event,

        else the function will be called only when event occurs on an entity or

        relation of the given type.

        """

        assert event in ALL_HOOKS, '%r NOT IN %r' % (event, ALL_HOOKS)

        assert (not event in SYSTEM_HOOKS or not etype), (event, etype)

        etype = etype or ''

        try:

            self._hooks[event][etype].append(function)

            self.debug('registered hook %s on %s (%s)', event, etype or 'any',

                       function.func_name)

        except KeyError:

            self.error('can\'t register hook %s on %s (%s)',

                       event, etype or 'any', function.func_name)

    def unregister_hook(self, function_or_cls, event=None, etype=''):

        """unregister a function to call when <event> occurs, or a Hook subclass.

        In the later case, event/type information are extracted from the given

        class.

        """

        if isinstance(function_or_cls, type) and issubclass(function_or_cls, Hook):

            for event, ertype in function_or_cls.register_to():

                for hook in self._hooks[event][ertype]:

                    if getattr(hook, 'im_self', None).__class__ is function_or_cls:

                        self._hooks[event][ertype].remove(hook)

                        self.info('unregister hook %s on %s (%s)', event, etype,

                                  function_or_cls.__name__)

                        break

                else:

                    self.warning("can't unregister hook %s on %s (%s), not found",

                                 event, etype, function_or_cls.__name__)

        else:

            assert event in ALL_HOOKS, event

            etype = etype or ''

            self.info('unregister hook %s on %s (%s)', event, etype,

                      function_or_cls.func_name)

            self._hooks[event][etype].remove(function_or_cls)

    def call_hooks(self, __event, __type='', *args, **kwargs):

        """call hook matching event and optional type"""

        if __type:

            self.info('calling hooks for event %s (%s)', __event, __type)

        else:

            self.info('calling hooks for event %s', __event)

        # call generic hooks first

        for hook in self._hooks[__event]['']:

            #print '[generic]', hook.__name__

            hook(*args, **kwargs)

        if __type:

            for hook in self._hooks[__event][__type]:

                #print '[%s]'%__type, hook.__name__

                hook(*args, **kwargs)

    def _init_hooks(self, schema):

        """initialize the hooks map"""

        for hook_event in ENTITIES_HOOKS:

            self._hooks[hook_event] = {'': []}

            for etype in schema.entities():

                self._hooks[hook_event][etype] = []

        for hook_event in RELATIONS_HOOKS:

            self._hooks[hook_event] = {'': []}

            for r_type in schema.relations():

                self._hooks[hook_event][r_type] = []

        for hook_event in SYSTEM_HOOKS:

            self._hooks[hook_event] = {'': []}

    def register_system_hooks(self, config):

        """register system hooks according to the configuration"""

        self.info('register core hooks')

        from cubicweb.server.hooks import _register_metadata_hooks, _register_wf_hooks

        _register_metadata_hooks(self)

        self.info('register workflow hooks')

        _register_wf_hooks(self)

        if config.core_hooks:

            from cubicweb.server.hooks import _register_core_hooks

            _register_core_hooks(self)

        if config.schema_hooks:

            from cubicweb.server.schemahooks import _register_schema_hooks

            self.info('register schema hooks')

            _register_schema_hooks(self)

        if config.usergroup_hooks:

            from cubicweb.server.hooks import _register_usergroup_hooks

            from cubicweb.server.hooks import _register_eproperty_hooks

            self.info('register user/group hooks')

            _register_usergroup_hooks(self)

            _register_eproperty_hooks(self)

        if config.security_hooks:

            from cubicweb.server.securityhooks import register_security_hooks

            self.info('register security hooks')

            register_security_hooks(self)

        if not self.verification_hooks_activated:

            self.deactivate_verification_hooks()

    def deactivate_verification_hooks(self):

        from cubicweb.server.hooks import (cardinalitycheck_after_add_entity,

                                        cardinalitycheck_before_del_relation,

                                        cstrcheck_after_add_relation,

                                        uniquecstrcheck_before_modification)

        self.warning('deactivating verification hooks')

        self.verification_hooks_activated = False

        self.unregister_hook(cardinalitycheck_after_add_entity, 'after_add_entity', '')

        self.unregister_hook(cardinalitycheck_before_del_relation, 'before_delete_relation', '')

        self.unregister_hook(cstrcheck_after_add_relation, 'after_add_relation', '')

        self.unregister_hook(uniquecstrcheck_before_modification, 'before_add_entity', '')

        self.unregister_hook(uniquecstrcheck_before_modification, 'before_update_entity', '')

#         self.unregister_hook(tidy_html_fields('before_add_entity'), 'before_add_entity', '')

#         self.unregister_hook(tidy_html_fields('before_update_entity'), 'before_update_entity', '')

    def reactivate_verification_hooks(self):

        from cubicweb.server.hooks import (cardinalitycheck_after_add_entity,

                                        cardinalitycheck_before_del_relation,

                                        cstrcheck_after_add_relation,

                                        uniquecstrcheck_before_modification)

        self.warning('reactivating verification hooks')

        self.verification_hooks_activated = True

        self.register_hook(cardinalitycheck_after_add_entity, 'after_add_entity', '')

        self.register_hook(cardinalitycheck_before_del_relation, 'before_delete_relation', '')

        self.register_hook(cstrcheck_after_add_relation, 'after_add_relation', '')

        self.register_hook(uniquecstrcheck_before_modification, 'before_add_entity', '')

        self.register_hook(uniquecstrcheck_before_modification, 'before_update_entity', '')

#         self.register_hook(tidy_html_fields('before_add_entity'), 'before_add_entity', '')

#         self.register_hook(tidy_html_fields('before_update_entity'), 'before_update_entity', '')

from cubicweb.selectors import yes

from cubicweb.appobject import AppObject

class autoid(type):

    """metaclass to create an unique 'id' attribute on the class using it"""

    # XXX is this metaclass really necessary ?

    def __new__(mcs, name, bases, classdict):

        cls = super(autoid, mcs).__new__(mcs, name, bases, classdict)

        cls.id = str(id(cls))

        return cls

class Hook(AppObject):

    __metaclass__ = autoid

    __registry__ = 'hooks'

    __select__ = yes()

    # set this in derivated classes

    events = None

    accepts = None

    enabled = True

    def __init__(self, event=None):

        super(Hook, self).__init__()

        self.event = event

    @classmethod

    def registered(cls, vreg):

        super(Hook, cls).registered(vreg)

        return cls()

    @classmethod

    def register_to(cls):

        if not cls.enabled:

            cls.warning('%s hook has been disabled', cls)

            return

        done = set()

        assert isinstance(cls.events, (tuple, list)), \

               '%s: events is expected to be a tuple, not %s' % (

            cls, type(cls.events))

        for event in cls.events:

            if event in SYSTEM_HOOKS:

                assert not cls.accepts or cls.accepts == ('Any',), \

                       '%s doesnt make sense on %s' % (cls.accepts, event)

                cls.accepts = ('Any',)

            for ertype in cls.accepts:

                if (event, ertype) in done:

                    continue

                yield event, ertype

                done.add((event, ertype))

                try:

                    eschema = cls.schema.eschema(ertype)

                except KeyError:

                    # relation schema

                    pass

                else:

                    for eetype in eschema.specialized_by():

                        if (event, eetype) in done:

                            continue

                        yield event, str(eetype)

                        done.add((event, eetype))

    def make_callback(self, event):

        if len(self.events) == 1:

            return self.call

        return self.__class__(event=event).call

    def call(self):

        raise NotImplementedError

class SystemHook(Hook):

    accepts = ()

from logging import getLogger

from cubicweb import set_log_methods

set_log_methods(HooksManager, getLogger('cubicweb.hooksmanager'))

set_log_methods(Hook, getLogger('cubicweb.hooks'))

# base classes for relation propagation ########################################

from cubicweb.server.pool import PreCommitOperation

class PropagateSubjectRelationHook(Hook):

    """propagate permissions and nosy list when new entity are added"""

    events = ('after_add_relation',)

    # to set in concrete class

    rtype = None

    subject_relations = None

    object_relations = None

    accepts = None # subject_relations + object_relations

    def call(self, session, fromeid, rtype, toeid):

        for eid in (fromeid, toeid):

            etype = session.describe(eid)[0]

            if not self.schema.eschema(etype).has_subject_relation(self.rtype):

                return

        if rtype in self.subject_relations:

            meid, seid = fromeid, toeid

        else:

            assert rtype in self.object_relations

            meid, seid = toeid, fromeid

        session.unsafe_execute(

            'SET E %s P WHERE X %s P, X eid %%(x)s, E eid %%(e)s, NOT E %s P'\

            % (self.rtype, self.rtype, self.rtype),

            {'x': meid, 'e': seid}, ('x', 'e'))

class PropagateSubjectRelationAddHook(Hook):

    """propagate on existing entities when a permission or nosy list is added"""

    events = ('after_add_relation',)

    # to set in concrete class

    rtype = None

    subject_relations = None

    object_relations = None

    accepts = None # (self.rtype,)

    def call(self, session, fromeid, rtype, toeid):

        eschema = self.schema.eschema(session.describe(fromeid)[0])

        execute = session.unsafe_execute

        for rel in self.subject_relations:

            if eschema.has_subject_relation(rel):

                execute('SET R %s P WHERE X eid %%(x)s, P eid %%(p)s, '

                        'X %s R, NOT R %s P' % (rtype, rel, rtype),

                        {'x': fromeid, 'p': toeid}, 'x')

        for rel in self.object_relations:

            if eschema.has_object_relation(rel):

                execute('SET R %s P WHERE X eid %%(x)s, P eid %%(p)s, '

                        'R %s X, NOT R %s P' % (rtype, rel, rtype),

                        {'x': fromeid, 'p': toeid}, 'x')

class PropagateSubjectRelationDelHook(Hook):

    """propagate on existing entities when a permission is deleted"""

    events = ('after_delete_relation',)

    # to set in concrete class

    rtype = None

    subject_relations = None

    object_relations = None

    accepts = None # (self.rtype,)

    def call(self, session, fromeid, rtype, toeid):

        eschema = self.schema.eschema(session.describe(fromeid)[0])

        execute = session.unsafe_execute

        for rel in self.subject_relations:

            if eschema.has_subject_relation(rel):

                execute('DELETE R %s P WHERE X eid %%(x)s, P eid %%(p)s, '

                        'X %s R' % (rtype, rel),

                        {'x': fromeid, 'p': toeid}, 'x')

        for rel in self.object_relations:

            if eschema.has_object_relation(rel):

                execute('DELETE R %s P WHERE X eid %%(x)s, P eid %%(p)s, '

                        'R %s X' % (rtype, rel),

                        {'x': fromeid, 'p': toeid}, 'x')